Recent advances in breast cancer treatment have made recognition of different prognostic groups mandatory. In addition, further experience with screening-detected lesions has resulted in the definition of new associations. Therapeutic approaches to these frequently microscopic lesions continue to be the source of much debate. The subtyping of ductal carcinoma in situ is also an area of continuing controversy. This article reviews recent studies of excellent-prognosis carcinomas as well as premalignant and other histologically defined lesions that indicate an increased risk for the development or recurrence of carcinoma. Advances in fine needle aspiration biopsy and in hormone receptor assays are also reviewed.